1. Field of the Invention
The present invention relates to a vehicular brake system that includes a brake actuator that enables brake assist to be carried out, the brake assist increasing a braking force exhibited by a wheel brake in response to a braking operation input by a vehicle driver in comparison with the braking force when it is unassisted.
2. Description of the Related Art
There are conventional vehicular brake systems in which when a vehicle driver carries out an emergency avoidance steering operation to avoid an obstacle, etc. the steering operation is aided by automatically braking a wheel on the inner side of the turn (see, for example, Japanese Patent Application Laid-open No. 9-142272). Also, there are conventional vehicular brake systems in which the braking force exhibited by a wheel brake is increased in response to a sudden braking operation by a vehicle driver (see, for example, Japanese Patent Application Laid-open No. 2001-287632).
An emergency avoidance steering operation is carried out by a vehicle driver in order to avoid an obstacle in front or to drive around a sharp bend, etc. Although the technique described in Japanese Patent Application Laid-open No. 9-142272 effectively achieves avoidance of an obstacle and driving around a sharp bend, the technique cannot cope with a secondary obstacle unexpectedly appearing in front. In this regard, it is expected that braking can be aided by the brake assist disclosed in Japanese Patent Application Laid-open No. 2001-287632 in order to avoid a collision with the secondary obstacle or moderate the impact during the collision. While the vehicle driver is carrying out the emergency avoidance steering operation, the driver is concentrating on the steering operation, so that it is difficult to carry out a braking operation. In the arrangement disclosed in Japanese Patent Application Laid-open No. 2001-287632, the brake assist is carried out in response to a sudden braking operation by the vehicle driver. Since it is difficult to carry out a sudden braking operation during the emergency avoidance steering operation or immediately after the emergency avoidance steering operation, even if the technique described in this patent application is applied as it is, it cannot be expected that the collision with the secondary obstacle will be avoided or the impact during the collision will be moderated.